Deck 4: Atmospheric Humidity

Question 1

Condensation occurs primarily when air is cooled, because as temperature drops the speed of the water molecules increases.

Answer 1

False

Question 2

The specific humidity and mixing ratio of an air parcel remain constant as long as water vapor is not added to or removed from the parcel.

Answer 2

True

Question 3

In the United States, the lowest dew point, and hence the driest air, is found in the Southwest, with the lowest values found in Arizona.

Answer 3

False

Question 4

If the amount of water vapor in a descending atmospheric air parcel remains constant, the specific humidity also remains constant.

Question 5

The relative humidity is often near 100 percent in polar regions.

Question 6

Comparing the three phases of water, molecules in the solid phase (ice)have the slowest vibrational speed, and molecules in the gaseous phase (water vapor)have the highest vibrational speeds.

Question 7

When the air temperature increases, the saturation vapor pressure decreases.

Question 8

Condensation differs from precipitation, because during precipitation water vapor is removed from the atmosphere, whereas during condensation solid or liquid water is removed from the atmosphere.

Question 9

During the winter, high relative humidity can irritate the mucus membranes in the nose and throat.

Question 10

Nighttime temperatures rarely drop below the dew point temperature because at saturation, latent heat of condensation is released into the air.

Question 11

Water in a glass will evaporate more quickly on a windy, warm, dry summer day than on a calm, cold, dry winter day.

Question 12

When the dew point is determined with respect to a flat surface of ice, it is called the ice point.

Question 13

Saturation is more likely to occur in cool air than in warm air.

Question 14

A region can have a high specific humidity and low relative humidity because large amounts of water vapor in the air and very high air temperatures will cause the specific humidity to be high, but the relative humidity to be low.

Question 15

The air's moisture content can be described by measuring the pressure exerted by the water vapor in the air.

Question 16

Saturation vapor pressure primarily depends upon air temperature.

Question 17

A sling psychrometer directly measures the relative humidity.

Question 18

Under saturated conditions, for every molecule that evaporates, one must condense, and no net loss of liquid or vapor molecules results.

Question 19

Plants give up moisture by a process called perspiration.

Question 20

A strand of human hair is known to increase by 2.5 percent as the relative humidity increases from 0 to 100 percent.

Question 21

Which of the following will increase the relative humidity in a home during the winter?

A)Increasing the thermostat setting
B)Increasing the temperature of the air inside the home
C)Sealing the house against drafts
D)Taking a shower and letting the air circulate through the home
E)Turning on the oven

Question 22

Which of the following always decreases in a rising parcel of air?

A)Relative humidity
B)Absolute humidity
C)Specific humidity
D)Mixing ratio
E)Dew point

Question 23

If the air temperature increased, with no addition or removal of water vapor, the actual vapor pressure would ____.

A)increase
B)decrease
C)stay the same
D)become greater than the saturation vapor pressure
E)become less than the saturation vapor pressure

Question 24

Evaporative coolers are primarily used in climates where the summers are ____.

A)hot and humid
B)hot and dry
C)cold and humid
D)cold and dry
E)moderate

Question 25

If the air temperature remains constant, evaporating water into the air will ____ the dew point and ____ the relative humidity.

A)increase; increase
B)increase; decrease
C)decrease; increase
D)decrease; decrease
E)not change; not change

Question 26

What will occur if a glass of water at a stable temperature is surrounded by saturated air?

A)The level of the water in the glass would slowly decrease.
B)The water's temperature would slowly increase.
C)The level of the water in the glass would not change.
D)The water's temperature would slowly decrease.
E)The level of the water in the glass would slowly increase.

Question 27

The density of water vapor in a given parcel of air is represented by the ____.

A)absolute humidity
B)relative humidity
C)mixing ratio
D)specific humidity
E)saturation vapor pressure

Question 28

What percentage of the nearly 1.5 quintillion gallons of water vapor that annually evaporates into the atmosphere evaporates from the oceans?

A)95 percent
B)85 percent
C)75 percent
D)50 percent
E)15 percent

Question 29

Suppose it is snowing outside and the air is saturated. The air temperature and dew point are both 15 degrees Fahrenheit, and the actual vapor pressure is 3 mb. If this air is brought indoors and warmed to 75 degrees Fahrenheit, what would the relative humidity of this air be, assuming that its moisture content does not change? (The saturation vapor pressure at 75 degrees Fahrenheit is 30 mb.)

A)5 percent
B)10 percent
C)30 percent
D)50 percent
E)100 percent

Question 30

Which of the following will increase in a rising parcel of air?

A)Saturation vapor pressure
B)Relative humidity
C)Mixing ratio
D)Air temperature
E)Air pressure

Question 31

When the temperature is 98 degrees Fahrenheit and the relative humidity is 55 percent, how would you classify the possible heat-related risk?

A)No caution or danger
B)Caution
C)Extreme caution
D)Danger
E)Extreme danger

Question 32

The time of day when the relative humidity reaches a maximum value is usually ____.

A)at the time when the air temperature is highest
B)in the middle of the afternoon
C)at the time when the air temperature is lowest
D)just before sunrise
E)about midnight

Question 33

The specific humidity and ____ of an air parcel remain constant as long as water vapor is not added to or removed from the parcel.

A)absolute humidity
B)mixing ratio
C)relative humidity
D)dew point
E)water vapor content

Question 34

A high water vapor pressure indicates a(n)____.

A)relatively large number of water vapor molecules in the air
B)relatively small number of water vapor molecules in the air.
C)relatively high rate of evaporation
D)abundant supply of condensation nuclei in the air
E)relatively high rate of precipitation

Question 35

Suppose the dew point of not outside air is the same as the dew point of the air indoors. If the door is opened and hot air replaces some of the cool air, then the new relative humidity indoors would be ____.

A)lower than before
B)higher than before
C)the same as before
D)impossible to tell from the information given
E)zero

Question 36

The temperature at which water boils depends mainly on ____.

A)air temperature
B)relative humidity
C)air pressure
D)air density
E)the specific heat of air

Question 37

As the air temperature increases, the air's capacity for water vapor ____.

A)increases
B)decreases
C)remains constant
D)is unrelated to air temperature and can either increase or decrease
E)drops by 50 percent

Question 38

If water vapor constitutes 3.5 percent of an air parcel whose total pressure is 1,000 mb, the water vapor pressure would be ____.

A)1,035 mb
B)35 mb
C)350 mb
D)965 mb
E)3,500 mb

Question 39

The percentage of water vapor present in the air compared to that required for saturation is the ____.

A)mixing ratio
B)absolute humidity
C)dew point
D)relative humidity
E)specific humidity

Question 40

What happens when air is saturated?

A)The air temperature equals the wet-bulb temperature.
B)The relative humidity is nonetheless less than 100 percent.
C)The air temperature is higher than the dew point temperature.
D)An increase in temperature will cause condensation to occur.
E)The temperature increases.

Question 41

This instrument uses a human or horse hair, or a synthetic fiber, to measure relative humidity.

A)Infrared hygrometer
B)Sling psychrometer
C)Hair hygrometer
D)Electrical hygrometer
E)Mechanical hygrometer

Question 42

Which of the following is the BEST indicator of the actual amount of water vapor in the air?

A)Air temperature
B)Saturation vapor pressure
C)Relative humidity
D)Dew point temperature
E)Mixing ratio

Question 43

The land occupies less than ____ percent of Earth's surface.

A)50
B)40
C)30
D)20
E)10

Question 44

____ law of partial pressure describes that the total pressure inside an air parcel is equal to the sum of all pressures of the individual gases present in the air parcel.

A)Hilton's
B)Dalton's
C)Dayton's
D)Hillary's
E)Ryan's

Question 45

Condensation is most likely to happen when air ____ and the speed of the water vapor molecules ____.

A)remains the same temperature; decreases
B)cools: increases
C)cools; decreases
D)warms; increases
E)warms; decreases

Question 46

Sun's energy transforms enormous quantities of liquid water into water vapor in a process called ____.

A)transformation
B)perspiration
C)precipitation
D)evaporation
E)condensation

Question 47

The ice-to-vapor phase transition is known as ____.

A)melting
B)evaporation
C)condensation
D)sublimation
E)deposition

Question 48

On a warm and windy day evaporation will be ____.

A)low
B)medium
C)the same as any other day
D)zero
E)high

Question 49

The partial pressure of water vapor is called the ____.

A)real vapor pressure
B)true vapor pressure
C)actual vapor pressure
D)actual water pressure
E)true liquid pressure

Question 50

The temperature to which air must be cooled to become saturated is the ____.

A)minimum temperature
B)Dew-point temperature
C)wet-bulb temperature
D)freezing point
E)maximum temperature

Question 51

In the gas state, water molecules are ____ in the liquid state.

A)farther apart than
B)the same distance apart as
C)double the distance apart as
D)three times the distance apart as
E)closer together than

Question 52

The instrument that measures humidity by measuring the amount of radiant energy absorbed by water vapor is the ____.

A)electrical hygrometer
B)infrared hygrometer
C)sling psychrometer
D)hair hygrometer
E)dew cell

Question 53

Which of the following BEST describes the wet-bulb temperature?

A)The highest temperature that can be attained by evaporating water into the air
B)The highest temperature that can be attained by condensing water from the air
C)The lowest temperature that can be attained by evaporating water into the air
D)The lowest temperature that can be attained by condensing water from the air
E)None of these are correct.

Question 54

The hot, desert air of the Sahara often contains ____ water vapor than the cold, polar air farther north, therefore has a ____ specific humidity.

A)less; lower
B)less; higher
C)less; similar
D)more; higher
E)more; lower

Question 55

The relationship between the mass of water vapor in an air parcel and the mass of all air in the same parcel (including vapor)is called ____.

A)specific humidity
B)relative humidity
C)absolute humidity
D)dew point
E)mixing ratio

Question 56

The average specific humidity is ____ in the warm, muggy tropics. As we move away from the tropics, it ____.

A)lowest; increases
B)highest; increases
C)intermediate; decreases
D)lowest; decreases
E)highest; decreases

Question 57

As the difference between the air temperature and the dew point increases, the relative humidity ____.

A)increases
B)decreases
C)remains constant at a value less than 100 percent
D)remains constant and equal to 100 percent
E)drops to zero

Question 58

The mass of water vapor in a given volume of air is called ____.

A)absolute humidity
B)relative humidity
C)mixing ratio
D)specific humidity
E)dew point

Question 59

Evaporation and transpiration from continental areas amount to only about ____ percent of the nearly 1.5 billion gallons of water vapor that annually evaporate into the atmosphere.

A)15
B)20
C)25
D)30
E)35

Question 60

If all of Earth's water vapor were to suddenly condense and fall as rain, it would be enough to cover the entire globe with ____ of water.

A)5 centimeters (2 inches)
B)100 meters
C)2.5 centimeters (1 inch)
D)1,000 meters
E)10 centimeters (4 inches)

Question 61

When both the air temperature and relative humidity are high and the air is nearly saturated with water vapor, body moisture does not readily ____.

A)transpire
B)perspire
C)saturate
D)condense
E)evaporate

Question 62

The primary factors that influence evaporation are ____________________, ____________________, and ____________________.

Question 63

Suppose saturated polar air has an air temperature and dew point of -10 degrees Celsius, and unsaturated desert air has an air temperature of 35 degrees Celsius and a dew point of 10 degrees Celsius. The desert air contains ____________________ water vapor and has a(n)____________________ relative humidity than the polar air.

Question 64

During the great Chicago heat wave of July 1995 the afternoon air temperature reached 106 degrees Fahrenheit at Midway Airport, followed by an overnight low temperature of only 84 degrees Fahrenheit. Many residents either had no air conditioning or could not afford to use it. More than ____ deaths occurred over five days.

A)35
B)70
C)350
D)700
E)3,500

Question 65

Chicago and many other cities in the United States have added neighborhood ____________________ and taken other steps to address the danger of heat waves.

Question 66

The ____ determines the amount of water vapor in the air by measuring the air's actual water vapor pressure.

A)aspirated psychrometer
B)hair hygrometer
C)sling psychrometer
D)dew-point hygrometer
E)dew cell

Question 67

The ____ the temperature of a gas, the faster its molecules move.

Question 68

The temperature difference between the dry bulb and the wet bulb is known as the ____.

A)dry-bulb depression
B)wet-bulb depression
C)dry-bulb inclination
D)wet-bulb inclination
E)bulb depression

Question 69

As the air temperature increases, with no addition of water vapor to the air, the relative humidity will ____________________.

Question 70

The ____________________ temperature is the temperature to which air would have to be cooled (with no change in air pressure or moisture content)for saturation to occur.

Question 71

Saturation vapor pressure depends primarily on ____.

A)the mixing ratio
B)altitude
C)air pressure
D)the dew point temperature
E)air temperature

Question 72

The cycle of moving and transforming water molecules from liquid to vapor and back to liquid again is called the ____________________.

Question 73

The heat index (HI)is used by the National Weather Service and combines ____ with ____ to determine an apparent temperature.

A)dew point temperature; mixing ratio
B)mixing ratio; saturation vapor pressure
C)actual vapor pressure; specific humidity
D)air temperature; relative humidity
E)air temperature; specific humidity

Question 74

The psychrometer is used to obtain ____ and ____.

A)dew point; relative humidity
B)apparent temperature; heat index
C)air pressure; saturation vapor pressure
D)absolute humidity; actual temperature
E)dew point temperature; specific humidity

Question 75

When the air temperature is below freezing, the saturation vapor pressure over water is ____________________ than the saturation vapor pressure over ice.

Question 76

If very cold air is brought indoors and warmed with no change in its moisture content, the saturation vapor pressure of this air will ____________________ and the relative humidity of this air will ____________________.

Question 77

In summer across North America, ____ vapor pressures are experienced over the drier Great Basin, especially Nevada; in winter, ____ values exist over the northern Great Plains into Canada.

A)the lowest; the lowest
B)the highest; the highest
C)the lowest; the highest
D)the highest; the lowest
E)intermediate; intermediate

Question 78

A temperature of 90 degrees Fahrenheit and a relative humidity of 90 percent would probably produce a heat index of ¬____ degrees Fahrenheit.

A)90
B)105
C)112
D)120
E)145

Question 79

Hot and dry summer days usually feel ____________________ than hot and wet summer days.

Question 80

An automated instrument that measures humidity, and consists of a flat plate coated with a film of carbon, is known as a(an)____.

A)psychrometer
B)thermometer
C)electrical hygrometer
D)dew cell
E)hair hygrometer